1. I'd suggest that you claim the VP before the roll. You are not affected by taxes by going there; you forego the action, you are affected (and shouldn't get the extra benefit of a free look at the taxes). Declare before the roll.
Ok. Decide first, roll later.
2. This one's easier: the warden gets the VP for every master builder assigned to the market. It's assigned there, whether you take the action or not, so the warden gets the VP.
The problem is that letting the workers work action (step 13) is after the market action (step 12). It is not at the same time.
So when player B decides to go for victory points, there are only 2 master builders assigned to the market when the warden 'works' in step 13. Or am I looking at this the wrong way?